Offshore oil and gas pipelines leading from stationary marine structures to the shore are widely used, and they serve as vital links in the fuel production process, transporting fossil fuels from drill sites to production facilities. There are a vast number of offshore platforms, oil wells, and mining rigs, for example, located in coastal water oil fields throughout the world, and pipelines are used to deliver the oil and natural gas from these offshore platforms to holding tanks on land. Each time a pipeline crosses another pipeline, a separation of the two must be maintained. The pipelines must also be stabilized in high-current areas, and all unburied pipelines must be protected from the possibility of impact damage. Also, there may be a need to add support to a depressed area in the sea floor before a pipeline or valve station is installed. The underwater valve stations and pipelines must be protected from trawling shrimp boat boards, etc. For convenience of maintenance and repair of the pipelines, the protective covering must sometimes be removed. The most conventional method of protecting the pipelines involves burlap bags.
Burlaps bags are the oldest method of protecting pipelines used on the ocean floor. Typically 60 lbs. burlaps are filled with pure sand or sand/cement at a sand plant. The burlap bags are then typically stacked bags per wooden pallet and shipped 14 or 15 pallets per truck. There are two common ways pure sand or sand/cement burlap bags are lowered into the ocean. The first method involves restacking the burlaps from its shipping pallet on the vessel into a cargo net, lowering the cargo net into the ocean, and dumping the burlap bags under water, so that divers can then place the burlap bags into position. The second, and most widely used method, employs two cables, which are pulled through the slots of the burlap bag pallet and then attached to a sling hanging down from above. Then, the pallet with burlap bags is picked-up and lowered into the ocean. Once the entire pallet is lowered underwater, a diver unhooks one cable; the crane lifts the sling, thereby dumping the burlap bags off of the pallet for the divers to place into position. The first method described above is extremely labor intensive, while the second method leaves wooden pallet pieces scattered in the ocean and exposes divers to nails and debris. The second method also lacks a degree of control, which further heightens safety concerns for the divers. Finally, the divers stack the burlap bags in position around the pipeline as needed. The type of fill material chosen for the burlap bags may also depend on the needs of the job.
The difference between the two types of burlap bag fill materials is that the pure sand does not harden, while the sand/cement turns into concrete after about 4 hours. Both burlap bags take the shape of what they are settling on. The pure sand burlaps are required as a temporary installation while the sand/cement burlaps are on the permanent side. Both pure sand and sand/cement burlap bags are more cost effective than the concrete mats, but are more labor intensive, requiring more time rigging-up each pallet and to position the individual bags. And while burlap bags with cement will harden to take the permanent shape of their area, they are more difficult to reapply in a manner that ensures a secure fit, due to their size and shape. So, standard burlap bags are not recommended when removal is an important factor. The present invention of the SlingBag is intended to provide a simple and effective means to pick-up the burlap bags from the wooden pallet, lower the burlap bags to the job site, and safely release the burlaps. The SlingBag with sand/cement burlap bags can also be left underwater, in order to provide both a secure fit and ease of removal and reapplication should repair work need to be performed on the pipeline (since the burlap bags are clustered effectively in larger groupings within the SlingBag).